To achieve a prosthetically optimized implant axis, a template, also called a drill-jig, is often used, e.g. an OP jig or CT splint. Templates are known for guiding dental implant drills for preparing the jaw bone and are intended to receive one or more dental implants. Templates of this kind are modeled manually or manufactured with the aid of a computer (CAM). They have drill holes that serve to guide a dental implant drill or the implant during a surgical intervention. Standardized metal drill sleeves (hereinafter standard drill sleeves) are often incorporated into the templates, e.g. polymerized in or pressed in, so as to increase the precision of the drilling operations. During a surgical intervention, the dental implant drill is guided by such a sleeve. The template thus serves to ensure that the drilling is carried out precisely in accordance with the optimal implant axes that have been determined at the planning stage.
In most implantation methods, the drilling is carried out in several steps. For example, a first drilling step is carried out with a pilot drill of small diameter, followed by a drilling step using a twist drill having the final diameter of the implant that is to be inserted. Depending on the method used, other drills, such as profile drills, with intermediate diameters or other cutting geometries may also be needed.
To apply this method, suitable reduction sleeves that correspond to the diameters of the dental drills used are fitted successively into the holes or standard drill sleeves of the templates. In the course of the drilling process, each one of the successive dental drills is inserted through the corresponding reduction sleeve and into the hole or drill sleeve.
The fact that the reduction sleeves are exchanged during the drilling process and that they typically have diameters of less than 6 mm, results in handling difficulties and even the risk of aspiration by the patient.
Reduction sleeves with grip-like extensions are known from WO 06/130067. The step-wise reduction in diameter is achieved by several reduction sleeves being stacked one inside another.
WO 06/014130 describes a reduction sleeve which is connected to a grip via a ball-and-socket hinge so as to be able to address different space situations in the patient's mouth.
WO 97/49351 discloses an implant-supported device for guiding a drill, with an auxiliary insert from which two reduction sleeves of identical diameter protrude and are held in a parallel position via a flat connection.
In order to achieve optimal guidance of the drill and thus optimal precision for the drilling process, the reduction sleeves need to have a certain height. This may lead to problems if the space above the implantation site is limited. Due to sterical hindrance, it may be difficult or even impossible to insert the dental drills through the reduction sleeves into the template.
In addition, the drilling portion of certain dental drills, in particular of profile drills, may be too wide for the reduction sleeve. In this case, it is not possible to insert the drill through the reduction sleeve and the drilling has to be performed without guidance. This may result in imprecise drilling and imperfect implant axes.